Asymmetric belt construction

ABSTRACT

A flexible, resilient belt of asymmetrical cross-section including opposite side wall portions, one of which is inclined at a larger angle than the other and a stress zone having an unequal stress-resisting capacity across the width of the belt with the greater stress-resisting capacity being concentrated in the area of the stress zone adjacent to the side wall portion having the larger angle. The belt is particularly useful in variable speed V-belt drives.

United States Patent Dorf et al.

[15] 3,656,359 [451 Apr. 18, 1972 [s41 ASYMMETRIC BELT CONSTRUCTION [72]inventors: Marvin L'. Dori; Leo C. Barnell, both of Lincoln, Nebr.

[73] Assignee: The Goodyear Tire & Rubber Company,

Akron, Ohio [22] Filed: Dec. 21, 1970 [2]] Appl. No.: 99,950

[52] US. Cl. ..74/234, 74/230.'l7 A, 74/237 [51] Int. Cl. ..Fl6g 5/00,Fl6g 1/22, Fl6h 55/22 [58] Field of Search ..74/234, 237, 230.17 C,230.17 A

[56] References Cited UNITED STATES PATENTS 3,365,967 11/1971 Moogk..74/230.l7A

Primary Examiner-Leonard H. Gerin Anomey-F. W. Brunner and Ronald P.Yaist [57] ABSTRACT A flexible, resilient belt of asymmetricalcross-section including opposite side wall portions, one of which isinclined at a larger angle than the other and a stress zone having anunequal stress-resisting capacity across the width of the belt with thegreater stress-resisting capacity being concentrated in the area of thestress zone adjacent to the side wall portion having the larger angle.The belt is particularly useful in variable speed V-belt'drives.

18 Claims, 4 Drawing Figures PATENFEUAPR 18 I972 33, 656,359

INVENTORS MARVIN L. DORF LEO C. BARNELL ATTOR NEY ASYMMETRIC BELTCONSTRUCTION I BACKGROUND OF THE INVENTION This invention relates totransmission belts and more particularly, to transmission belts of the Vtype having an asymmetrical cross-section which are particularly usefulon variable speed V-belt drives. This invention has specific applicationto a novel belt structure for an asymmetric V-belt to improve itsoperability in such drives.

V-belts of asymmetrical cross-section are known in the art. These beltsusually have the customary trapezoidal cross-sectional configuration buthave one vertical or substantially vertical side wall and an oppositeside wall inclined at an oblique angle thereto, as measured with respectto the vertical centerline of the belt section. The asymmetric V-beltsare designed to operate with pulleys of similar cross-sectionalconfiguration, for example, in variable speed drives. A belt of thisparticular cross-sectional configuration offers certain advantages overa conventional V-belt whose side walls are inclined at approximatelyequal angles in that it is more easily maintained in its running planeduring regulationadjustments of the drive. For example, Moogk, U.S. Pat.No. 3,365,967 discloses a stepless, variable V-belt driving gear whichincludes an asymmetric V-belt having one side wall inclined up to 1 andthe opposite side wall inclined by about 19. The stress of strength zoneof this V-belt includes reinforcing cords of the same or similar modulusmaterial uniformly disposed across its entire width so that higher powermay be transmitted by the belt.

Some difficulties, however, have been encountered with a V-belt ofasymmetrical cross-section having the construction of the type disclosedin this previously mentioned prior art reference. For example, after aperiod of operation in the belt drive, the asymmetric V-belt becomesdistorted in length and tends to bow laterally between the sheaves orpulleys to such an extent that if the belt is removedfrom the drive andlaid on a horizontal surface, the belt then in effect becomes ahorizontal section of a cone. The asymmetric V-belt also tends to ridehigher in the sheaves or pulleys on the side of the belt having thelarger side wall angle. Due to the disadvantages listed above, theefficiency and useful life of this type belt has been appreciablyreduced.

These problems are likely attributable to the fact that the beltstretches more on its large angle side than on its small angle side.This believed to be, at least in large measure, due to the unequalstress distribution which is created across the 1 width of the beltduring its operation in the drive since the large angle side is underthe greater stress. It has been found unexpectedly that thebeforementioned disadvantages of the asymmetric V-belt are overcome bythe belt structure of the present invention having a stress zone ofunequal stress-resisting capacity which will be hereinafter more fullydescribed.

OBJECTS OF THE INVENTION It is a primary object of the present inventionto provide a V-belt of asymmetrical cross-section which will haveimproved service life and operability. I

It is another important object of the present invention to provide aV-belt of asymmetrical cross-section which will operate more uniformlyin a belt drive assembly and will not become distorted in length and bowlaterally during its operation around and between the pulleys in a beltdrive assembly.

It is another object of this invention to provide an asymmetric V-beltstructure which will result in a substantially equal stress distributionacross the width of the belt during its operation on a variable speeddrive.

Other objects and advantages of this inventionwill become apparenthereinafter as the description thereof proceeds, the novel features,arrangements and combinations being clearly pointed out in thespecification as well as the claims thereunto appended.

It has been found, in accordance with the teachings of the I presentinvention, that the beforementioned objects can be accomplished byproviding a flexible, resilient belt having a body portion ofasymmetrical cross-section which includes a first base or bottomportion; a second base or top portion spaced from the bottom portion;opposite side wall portions joining the base portions, including a firstside wall portion defining one longitudinal edge of the belt and asecond side wall portion defining the opposite longitudinal edge of thebelt and inclined at a greater angle than the first side wall portion,as measured with reference to the vertical centerline of the beltsection; and a stress zone disposed between the base portions havingunequal stress-resisting capacity across the width of the belt with agreater stress-resisting capacity concentrated in an area of the beltadjacent to the second side wall portion.

In the preferred belt construction, the stress zone includes at leastone stress-resisting member extending longitudinally of the belt anddisposed transversely thereof in at least the area of the stress zonewhich is adjacent to the second side wall portion. In this regard it ispreferred that each of the stress-resisting members be disposed inhelical wraps across the belt in the stress zone with each wrap of thehelix positioned inspaced side-by-side relationship to form a pluralityor group of spaced elements. The elements preferably terminate at asubstantial distance from the first side wall portion so that the areaof the stress zone adjacent to the first side wall portion is at leastsubstantially unreinforced.

It is also possible that the stress zone include a second group ofelements therein disposed adjacent to the first side wall portion withthe elements of the second group being spaced at a greater distance fromeach other than the elements of the first mentioned group. In addition,the elements may be disposed transversely across substantially theentire width of the belt and include one group of elements adjacent tothe first side wall portion composed of a relatively low modulusmaterial and another group of elements adjacent to the second side wallportion composed of a relatively high modulus material.

BRIEF DESCRIPTION OF THE DRAWINGS In the drawings:

FIG. 1 is a fragmentary view partially in section of a belt driveassembly including the transmission belt of the present invention shownin its operating position around the pulleys of the drive;

FIG. 2 is an enlarged fragmentary sectional view taken on line 2-2 ofFIG. 1;

FIG. 3 is a sectional view showing a modification of the invention asshown in FIG. 2; and

FIG. 4 is a sectional view of still another modification of theinvention as shown in FIG. 2.

DESCRIPTION OF THE PREFERRED EMBODIMENTS Referring now to the drawings,in FIGS. 1 and2 a part of a belt drive assembly 10, for example of thevariable speed type, is shown including a flexible transmission belt 11which is trained around rigid metallic sheaves or pulleys 12.

The specific features of the belt 11 are best seen in FIG. 2. Asillustrated, the belt 11 is of a reinforced unitary construction andincludes a body portion 13 of flexible, resilient material. This ispreferably a flexible, polymeric material such as natural or syntheticrubber or other elastomeric materials.

The body portion 13 has an asymmetrical, generally trapezoidalcross-section which includes a base portion 14 which may be referred toin this instance, as viewed in FIG. 2, as the bottom or minor base ofthe belt 11, and-another base portion 15 spaced from the first mentionedbase portion 14 which in this instance, as viewed in FIG. 2, may bereferred to as the top or major base of the belt 11. Opposite side wallportions 16 and 17 join the base portions 14 and 15. A first side wallportion 16 defines one longitudinal extending edge of the belt 11 and asecond side wall portion 17 defines the opposite longitudinal extendingedge of the belt 11 and is inclined at a greater angle than the firstside wall portion 16 as measured with reference to the verticalcenterline of the belt section. The incline of side wall portion 16 isdesignated as angle 1: and the incline of side wall portion 17 isdesignated as angle y. Preferably, the first side wall portion 16 issubstantially parallel to the vertical centerline of the belt sectionand angle x is from about degrees to about degrees as measured withrespect thereto. Similarly, the second side wall portion is inclined atan angle y of from about 13 to about with respect to the verticalcenterline of the belt section. For optimum operating conditions, it isrecommended that the angle x be from about 1 to about 2 and that theangle y be about 19.

The body portion 13 further includes a stress or strength zone 18disposed between the base portions 14 and 15. The stress zone 18 is theload-carrying section of the belt 11 which is subjected to tensionstress as the belt 11 is running in its longitudinal extent between thepulleys 12. This same zone or section 18 is commonly referred to as theneutral axis section when the belt is bending around the pulleys since,at that moment, it is neither under tension nor compression. The stresszone 18 has an unequal stress-resisting capacity across the width of thebelt 11 with the lesser stress-resisting capacity being concentrated inan area A adjacent to the first or substantially vertical side wallportion 16 and the greater stressresisting capacity being concentratedin an area B thereof adjacent to the second side wall portion 17 or theside wall portion inclined at the largest angle with respect to thevertical centerline of the belt section.

In the preferred form of the invention, as most clearly shown in FIG. 2,the unequal stress-resisting properties are accomplished by a structurein which the stress zone 18 includes at least one stress-resistingmember 19 extending longitudinally of the belt 11 and disposedtransversely thereof in at least the area B of the zone adjacent to thesecond side wall portion 17 of the belt 11. Usually, the member 19 is inthe form of a single cord which is disposed in helical wraps across thestress zone 18 in area B with each wrap of the cord positioned in spacedside-byside relationship to form a plurality or group 20 of spacedelements 20'. The cord may be either of a twisted fiber or filamentconstruction referred to as cable cord or tire cord which is composed ofany of the well-known textile fabric materials, such as cotton, nylon,rayon or polyester or combinations thereof and may also be composed ofsuch materials as steel wire or fiber glass. The group 20 of elements20' terminates at a substantial distance from the first side wallportion 16 so that the area A of the zone 18 is at least substantiallyunreinforced. It has been found that the unequal stress-resistingcapacity thus created in the zone 18 by the foregoing structure resultsin a more evenly or uniformly distributed stress across the width of thebelt 11, thereby preventing the stretch or longitudinal distortion ofthe large angle side wall 17 of the belt 11 with its resultant lateralbow. In addition, the belt 11 also rides more evenly in the pulleys 12and its useful life is greatly increased.

It should also be understood that provided it is disposed as describedabove, the stress-resisting member 19 can also be in other forms such asa square-woven fabric layer of conventional materials and construction.

The belts 11 are manufactured in a customary manner as for example, byassembling and vulcanizing the belt components into a unitaryconstruction by means of conventional equipment well-known for thesepurposes.

In addition, it is apparent that many other various belt constructionsare possible. For instance, the belt may also include a fabric envelopesurrounding the body portion and may or may not be of a cogged or archedconstruction well known in the art.

The pulleys 12 have faces or surfaces which correspond generally to thecross-sectional configuration of the belt 11. For example, each pulley12 includes a section 21 having a substantially planar belt contactingsurface 22 and an opposite section 23 having a conical belt contactingsurface 24. The substantially vertical planar side wall portion 16 ofthe belt 11 contacts the surface 22 of the planar pulley section 21 andthe second pulley contacting side wall portion 17 of the belt 11contacts the surface 24 of the conical pulley section 23 during theoperation of the belt 11 in the drive 10. Accordingly, the portion 17 issubjected to the greater stress during the operation of the belt 11since it is in almost complete contact and engagement with the pulleysurface 24 whereas the portion 16 is not actually in severe workingcontact with pulley surface 22. The structure of this invention resultsin a more even distribution of stress across the belt and largelyeliminates or significantly reduces the undue stretching of only oneside wall portion of the belt.

Of course, it is to be understood that the belts of this invention canbe used with many other belt drive assemblies and consequently, manyvarious pulley arrangements are possible. For instance, it has beenfound that these belts are particularly useful as part of variable speeddrives for small track vehicles such as snowmobiles.

FIG. 3 shows a modification of the invention in which the stress zone 25of an asymmetric V-belt 26 includes a first group 27 of elements 27disposed adjacent to the second or large angle side wall portion 28 ofthe belt 26 in area B of the zone 25 and a second group 29 elements 29are disposed adjacent to the first or small angle side wall portion 30of the belt 26 in area A of the zone 25. In this embodiment, theelements 29' of the second group 29 are spaced at a greater distancefromeach other than the elements 27 of the first group 27 so that anunequal stress-resisting capacity is thereby achieved with the greaterstress-resisting capacity concentrated in the area B.

In FIG. 4,'a modification of the invention is shown in which the unequalstress-resisting capacity of the stress zone 31 is achieved by providingreinforcing elements across substantially the entire width of the belt32. The zone 31 in this instance includes one group 33 of elements 33'adjacent to the first or small side wall angle portion 34 in area A ofthe zone 31 which is composed of relatively low modulus material.Another group 35 of elements 35 is disposed adjacent to the second orlarge angle side wall portion in area B of the zone 31 and is composedof relatively high modulus material. For example, the elements 33' ofthe first group 33 may be cords composed of conventional reinforcingmaterial such as cotton, nylon, rayon and polyester and the elements 35'of the second group 35 may be cords composed of high modulus materialsuch as steel or fiber glass. Alternatively, the elements 33' and 35 maybe cords composed of the same material but having differing moduli dueto the manner in which the elements or cords of each group 33 and 35have been processed.

Since the belt structures, as shown in FIGS. 3 and 4, require that thereinforcing elements or cords be disposed in the stress zone in a moreexacting manner than the structure disclosed in FIG. 2, they mayprobably be considered as less desirable from an economic standpoint.

It should be apparent to those skilled in the art that this inventionprovides a belt structure for an asymmetric V-belt which will accomplishthe objects of this invention by correcting the unequal stretching ofthe belt which has been experienced with previous belt structures ofthis type in which the reinforcing cord members have been disposeduniformly across the belt's width and have been composed of material ofrelatively the same modulus.

While certain representative embodiments and details have been shown forthe purpose of illustrating the invention, it will be apparent to thoseskilled in the art that various changes and modifications may be madetherein without departing from the spirit or scope of the invention.

What is claimed is:

l. A flexible resilient belt having a body portion of asymmetriccross-section comprising:

A. a first base portion;

B. a second base portion spaced therefrom;

C. opposite side wall portions joining said first and second baseportions including: 1. a first side wall portion defining onelongitudinal edge of the belt, and

2. a second side wall portion defining the opposite longitudinal edge ofthe belt, inclined at a greater angle than said first side wall portionas measured with reference to the vertical centerline of the beltsection; and

D. a stress zone disposed between said first and second base portionshaving unequal stress-resisting capacity across the width of the beltwith the greater stress-resisting capacity concentrated in an areathereof adjacent to said second side wall portion.

2. The belt as claimed in claim 1 wherein said first side wall portionis substantially parallel to the vertical centerline of the beltsection.

3. The belt as claimed in claim 2 wherein with respect to said verticaleenterline, said first side wall portion is inclined at an angle of fromabout to about and said second side wall portion is inclined at an angleof from about 13 to about 20.

4. The belt as claimed in claim 3 wherein said first side wall portionhas an angle of from about 1 to about 2 and said second side wallportion has an angle of about 19.

5. The belt as claimed in claim 1 wherein said stress zone includes atleast one stress-resisting member extending longitudinally of the beltand disposed transversely thereof in at least the area of said stresszone adjacent to said second side wall portion.

6. The belt as claimed in claim 5 wherein said member is disposed inhelical wraps across the belt-in said stress zone with each wrap thereofpositioned in spaced side-by-side relationship to form a plurality ofspaced elements.

7. The belt as claimed in claim 6 wherein one group of elementsterminates at a substantial distance from said first side wall portionso that the area of said stress zone adjacent thereto is at leastsubstantially unreinforced.

8. The belt as claimed in claim 7 wherein said stress zone furtherincludes a second group of elements therein disposed adjacent to saidfirst side wall portion with the elements of said second group beingspaced at a greater distance from each other than the elements of saidfirst mentioned group.

9. The belt as claimed in claim 6 wherein said elements are disposedtransversely across substantially the entire width of the belt andinclude one group of said elements adjacent to said first side wallportion composed of relatively low modulus material and another group ofsaid elements adjacent to said second side wall portion composed ofrelatively high modulus material.

10. In a drive belt assembly including the combination of a V-belt offlexible, polymeric material having a body portion of asymmetricalcross-section, a pair of pulleys on which the belt is mounted, at leastone of which includes a section having a substantially planarbelt-contacting surface and an opposite section having a conicalbelt-contacting surface, said belt comprising first and second spacedbase portions and opposite side wall portions joining said base portionsincluding a first substantially vertical planar side wall portion forcontacting the planar pulley section and a second pulley-contacting sidewall portion opposite said first side wall and disposed at an obliqueangle thereto for contacting the conical pulley section, the improvementwherein said belt includes a stress zone disposed between said first andsecond base portions having unequal stress-resisting capacity across thewidth of the belt with the greater stress-resisting capacityconcentrated in an area thereof adjacent to said second side wallportion.

11. The belt as claimed in claim 10 wherein said first side wall portionis inclined at an angle of from about 0 to about 5 and said second sidewall portion is inclined atan angle of from about 13 to about 12. Thebelt as claimed in claim 11 wherein said first side I wall portion hasan angle of from about 1 to about 2 and said second side wall portionhas an angle of about 19.

13. The belt as claimed in claim 10 wherein said stress zone includes atleast one stress-resisting member extending longitudinally of the beltand disposed transversely thereof in at east the area of said stresszone ad acent to said second side wall portion.

14. The belt as claimed in claim 13 wherein said member is disposed inhelical wraps across the belt in said stress zone with each wrap thereofpositioned in spaced side-by-side relationship to form a plurality ofspaced elements.

15. The belt as claimed in claim 14 wherein one group of elementsterminates at a substantial distance from said first side wall portionso that the area of said stress zone adjacent thereto is at leastsubstantially unreinforced.

16. The belt as claimed in claim 15 wherein said stress zone furtherincludes a second group of elements therein disposed adjacent to saidfirst side wall portion with the elements of said second group beingspaced at a greater distance from each other than the elements of saidfirst mentioned group.

17. The belt as claimed in claim 16 wherein said elements are disposedtransversely across substantially the entire width of the belt andinclude one group of said elements adjacent to said first side wallportion composed of relatively low modulus material and another group ofsaid elements adjacent to said second side wall portion composed ofrelatively high modulus material.

18. The belt as claimed in claim 17 wherein said first group of elementsare in the form of textile cords composed of material selected from thegroup consisting of cotton, nylon, rayon and polyester and said secondgroup of elements are in the form of high strength filaments composed ofmaterial selected from the group consisting of steel and fiber glass.

1. A flexible resilient belt having a body portion of asymmetriccross-section comprising: A. a first base portion; B. a second baseportion spaced therefrom; C. opposite side wall portions joining saidfirst and second base portions including:
 1. a first side wall portiondefining one longitudinal edge of the belt, and
 2. a second side wallportion defining the opposite longitudinal edge of the belt, inclined ata greater angle than said first side wall portion as measured withreference to the vertical centerline of the belt section; and D. astress zone disposed between said first and second base portions havingunequal stress-resisting capacity across the width of the belt with thegreater stress-resisting capacity concentrated in an area thereofadjacent to said second side wall portion.
 2. a second side wall portiondefining the opposite longitudinal edge of the belt, inclined at agreater angle than said first side wall portion as measured withreference to the vertical centerline of the belt section; and D. astress zone disposed between said first and second base portions havingunequal stress-resisting capacity across the width of the belt with thegreater stress-resisting capacity concentrated in an area thereofadjacent to said second side wall portion.
 2. The belt as claimed inclaim 1 wherein said first side wall portion is substantially parallelto the vertical centerline of the belt section.
 3. The belt as claimedin claim 2 wherein with respect to said vertical centerline, said firstside wall portion is inclined at an angle of from about 0* to about 5*and said second side wall portion is inclined at an angle of from about13* to about 20* .
 4. The belt as claimed in claim 3 wherein said firstside wall portion has an angle of from about 1* to about 2* and saidsecond side wall portion has an angle of about 19* .
 5. The belt asclaimed in claim 1 wherein said stress zone includes at least onestress-resisting member extending longitudinally of the belt anddisposed transversely thereof in at least the area of said stress zoneadjacent to said second side wall portion.
 6. The belt as claimed inclaim 5 wherein said member is disposed in helical wraps across the beltin said stress zone with each wrap thereof positioned in spacedside-by-side relationship to form a plurality of spaced elements.
 7. Thebelt as claimed in claim 6 wherein one group of elements terminates at asubstantial distance from said first side wall portion so that the areaof said stress zone adjacent thereto is at least substantiallyunreinforced.
 8. The belt as claimed in claim 7 wherein said stress zonefurther includes a second group of elements therein disposed adjacent tosaid first side wall portion with the elements of said second groupbeing spaced at a greater distance from each other than the elements ofsaid first mentioned group.
 9. The belt as claimed in claim 6 whereinsaid elements are disposed transversely across suBstantially the entirewidth of the belt and include one group of said elements adjacent tosaid first side wall portion composed of relatively low modulus materialand another group of said elements adjacent to said second side wallportion composed of relatively high modulus material.
 10. In a drivebelt assembly including the combination of a V-belt of flexible,polymeric material having a body portion of asymmetrical cross-section,a pair of pulleys on which the belt is mounted, at least one of whichincludes a section having a substantially planar belt-contacting surfaceand an opposite section having a conical belt-contacting surface, saidbelt comprising first and second spaced base portions and opposite sidewall portions joining said base portions including a first substantiallyvertical planar side wall portion for contacting the planar pulleysection and a second pulley-contacting side wall portion opposite saidfirst side wall and disposed at an oblique angle thereto for contactingthe conical pulley section, the improvement wherein said belt includes astress zone disposed between said first and second base portions havingunequal stress-resisting capacity across the width of the belt with thegreater stress-resisting capacity concentrated in an area thereofadjacent to said second side wall portion.
 11. The belt as claimed inclaim 10 wherein said first side wall portion is inclined at an angle offrom about 0* to about 5* and said second side wall portion is inclinedat an angle of from about 13* to about 20* .
 12. The belt as claimed inclaim 11 wherein said first side wall portion has an angle of from about1* to about 2* and said second side wall portion has an angle of about19* .
 13. The belt as claimed in claim 10 wherein said stress zoneincludes at least one stress-resisting member extending longitudinallyof the belt and disposed transversely thereof in at least the area ofsaid stress zone adjacent to said second side wall portion.
 14. The beltas claimed in claim 13 wherein said member is disposed in helical wrapsacross the belt in said stress zone with each wrap thereof positioned inspaced side-by-side relationship to form a plurality of spaced elements.15. The belt as claimed in claim 14 wherein one group of elementsterminates at a substantial distance from said first side wall portionso that the area of said stress zone adjacent thereto is at leastsubstantially unreinforced.
 16. The belt as claimed in claim 15 whereinsaid stress zone further includes a second group of elements thereindisposed adjacent to said first side wall portion with the elements ofsaid second group being spaced at a greater distance from each otherthan the elements of said first mentioned group.
 17. The belt as claimedin claim 16 wherein said elements are disposed transversely acrosssubstantially the entire width of the belt and include one group of saidelements adjacent to said first side wall portion composed of relativelylow modulus material and another group of said elements adjacent to saidsecond side wall portion composed of relatively high modulus material.18. The belt as claimed in claim 17 wherein said first group of elementsare in the form of textile cords composed of material selected from thegroup consisting of cotton, nylon, rayon and polyester and said secondgroup of elements are in the form of high strength filaments composed ofmaterial selected from the group consisting of steel and fiber glass.